(a) Field
The subject matter disclosed generally relates to blinds. More specifically, it relates to blinds which selectively reflect sunlight.
(b) Related Prior Art
Heating and air conditioning of buildings are a major issue in energetic resource management. Together, they amount to a significant fraction of the maintenance cost of building. When buildings are large, the cost of maintaining a comfortable temperature is important, and the impact on environmental resource consumption can be significant. Insulation is of course a primary factor, but the configuration of windows plays a role in the thermal energy balance of the building, since this is where the sunlight penetrates into the building to heat it from inside.
Many technologies were developed to address this issue, with mixed results. Some technologies involve placing a reflector either inside or outside the window. It has the disadvantage of blocking sunlight even during winter times, when sunlight is desired inside the building. Placing a blocking structure (blinds, panels) close to the window inside the building has the disadvantage of absorbing sunlight during summer times, producing heat within the building. If blinds are installed outside, they are vulnerable to weather events.
More recent technologies involving architectural solutions, such as horizontal structures above windows to hide sunlight when the sun has a high inclination, provide a suitable solution for new buildings. However, this solution is more costly and is better suited for new buildings.
Some technologies which address this issue have been developed. For example, document JP2005240469A illustrates a window with a glass shaped as to reflect sunlight if the incoming sunlight has a high inclination, and to let the sunlight pass through the window if the inclination is low. This technology is however costly, sophisticated and fragile, since it involves shaping glass. Furthermore, it cannot be removed by a user.
Document DE19823758A1 shows a blind comprising reflectors with multiple surfaces with incremental inclination thereon to provide the same effect. However, the shape is complicated to manufacture and therefore expensive. Furthermore, the user can modify the general inclination of the blinds to have them more or less effective, which can lead to sub-optimal configurations for long periods of time.
There is therefore a need for a structure, such as a blind, that would reflect sunlight away when its inclination is high (summer) and let the sunlight pass through when its inclination is low (winter), the blind having a simple shape which is easy and inexpensive to produce, that can replace standard blinds in houses, offices and other buildings.